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71.
María Uriarte Charles B. Yackulic Yili Lim Javier A. Arce-Nazario 《Landscape Ecology》2011,26(8):1151-1164
There is a pressing need to understand the consequences of human activities, such as land transformations, on watershed ecosystem
services. This is a challenging task because different indicators of water quality and yield are expected to vary in their
responsiveness to large versus local-scale heterogeneity in land use and land cover (LUC). Here we rely on water quality data
collected between 1977 and 2000 from dozens of gauge stations in Puerto Rico together with precipitation data and land cover
maps to (1) quantify impacts of spatial heterogeneity in LUC on several water quality indicators; (2) determine the spatial
scale at which this heterogeneity influences water quality; and (3) examine how antecedent precipitation modulates these impacts.
Our models explained 30–58% of observed variance in water quality metrics. Temporal variation in antecedent precipitation
and changes in LUC between measurements periods rather than spatial variation in LUC accounted for the majority of variation
in water quality. Urbanization and pasture development generally degraded water quality while agriculture and secondary forest
re-growth had mixed impacts. The spatial scale over which LUC influenced water quality differed across indicators. Turbidity
and dissolved oxygen (DO) responded to LUC in large-scale watersheds, in-stream nitrogen concentrations to LUC in riparian
buffers of large watersheds, and fecal matter content and in-stream phosphorus concentration to LUC at the sub-watershed scale.
Stream discharge modulated impacts of LUC on water quality for most of the metrics. Our findings highlight the importance
of considering multiple spatial scales for understanding the impacts of human activities on watershed ecosystem services. 相似文献
72.
Casado FJ Sánchez AH De Castro A Rejano L Beato VM Montaño A 《Journal of agricultural and food chemistry》2011,59(6):2403-2409
Chemical and sensorial changes related to the use of benzoates and ascorbic acid as additives in packed fermented vegetables were investigated. For this, three selected vegetables (green olives, cucumbers, and caperberries) stored under different conditions (glass or plastic containers, ambient or refrigerated storage) were used. In all cases, benzoic acid remained unchanged (glass bottle) or decreased slightly (plastic pouch) at prolonged storage. Ascorbic acid was partially or totally degraded during storage, the degradation rate depending on the storage conditions and the vegetable matrix. Benzene levels higher than 10 μg/L were found in cucumbers and caperberries containing both additives, but only when packed in plastic pouches and after prolonged storage at room temperature. In these conditions, an appreciable browning of brine, related to AA degradation, was also found. The use of benzoate alone had a significant influence on vegetable color, but flavor was not significantly affected at the benzoate levels tested. On the basis of the present study, benzoates should be removed from fermented vegetable formulations containing ascorbic acid to eliminate possible benzene formation during long-term storage. 相似文献
73.
Lara Vilar del Hoyo M. Pilar Martín Isabel F. Javier Martínez Vega 《European Journal of Forest Research》2011,130(6):983-996
About 90% of the wildland fires occurred in Southern Europe are caused by human activities. In spite of these figures, the
human factor hardly ever appears in the definition of operational fire risk systems due to the difficulty of characterising
it. This paper describes two spatially explicit models that predict the probability of fire occurrence due to human causes
for their integration into a comprehensive fire risk–mapping methodology. A logistic regression technique at 1 × 1 km grid
resolution has been used to obtain these models in the region of Madrid, a highly populated area in the centre of Spain. Socio-economic
data were used as predictive variables to spatially represent anthropogenic factors related to fire risk. Historical fire
occurrence from 2000 to 2005 was used as the response variable. In order to analyse the effects of the spatial accuracy of
the response variable on the model performance (significant variables and classification accuracy), two different models were
defined. In the first model, fire ignition points (x, y coordinates) were used as response variable. This model was compared with another one (Kernel model) where the response variable
was the density of ignition points and was obtained through a kernel density interpolation technique from fire ignition points
randomly located within a 10 × 10 km grid, which is the standard spatial reference unit established by the Spanish Ministry
of Environment, Rural and Marine Affairs to report fire location in the national official statistics. Validation of both models
was accomplished using an independent set of fire ignition points (years 2006–2007). For the validation, we used the area
under the curve (AUC) obtained by a receiver-operating system. The first model performs slightly better with a value of AUC
of 0.70 as opposed to 0.67 for the Kernel model. Wildland–urban interface was selected by both models with high relative importance. 相似文献
74.
Ordóñez RM Zampini IC Rodríguez F Cattaneo F Sayago JE Isla MI 《Journal of agricultural and food chemistry》2011,59(16):8655-8660
In this study, antioxidant activities in free-radical-mediated oxidative systems and the genotoxic/antigenotoxic effects of two proteins with molecular mass around 17 kDa, purified from Solanum betaceum fruits (cyphomine) and Solanum tuberosum tubers (solamarine), were investigated. Both proteins inhibited uric acid formation with IC(50) values between 55 and 60 μg/mL, and both proteins were able to reduce oxidative damage by scavenging hydroxyl radicals and superoxide anion in a dose-dependent manner. Furthermore, the DPPH? reduction assay showed SC(50) values of 55-73 μg/mL. Cyphomine and solamarine were able to retain their antioxidant activity after heat treatment at 80 °C for 15 min. Allium cepa and Salmonella /microsome assays showed no genotoxic and mutagenic effects. Solamarine showed an antimutagenic effect against a direct mutagen (4-nitro-o-phenylenediamine). Consequently, the present study showed that the investigated proteins are promising ingredients for the development of functional foods with a beneficial impact on human health and an important source for the production of bioactive peptides. 相似文献
75.
Cinta Prieto Francisco Javier Martínez-Lobo Francisco Díez-Fuertes Patricia Aguilar-Calvo Isabel Simarro José María Castro 《Veterinary journal (London, England : 1997)》2011,189(3):323-329
Disease exacerbation was observed in pigs challenged with virulent porcine reproductive and respiratory syndrome virus (PRRSV) following immunisation with a recombinant GP5 sub-unit PRRSV vaccine (rGP5) produced in E. coli. Eighteen animals were divided into three experimental groups: group A were immunised twice IM with rGP5, 21 days apart; group B acted as positive controls (challenged but not immunised); and group C were negative controls. Pigs in groups A and B were challenged 21 days after the second immunisation of the group A animals. Following challenge, three pigs given rGP5 exhibited more severe clinical signs than the positive controls, including respiratory distress and progressive weight-loss. Although not statistically significant, the more severe disease exhibited by group A animals may suggest previous immunisation as a contributory factor. The mechanisms of these findings remain unclear and no association could be established between the severity of disease, non-neutralising antibody concentrations and tissue viral loads. 相似文献
76.
Martín-Cabrejas MA Ariza N Esteban R Mollá E Waldron K López-Andréu FJ 《Journal of agricultural and food chemistry》2003,51(5):1254-1259
The effect of different conditions of pea germination on dietary fiber (DF) composition was studied. Insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) were subjected to acid hydrolysis, and the resultant neutral sugars, uronic acids, and Klason lignin were quantified. Germinated peas exhibited significantly higher contents of total dietary fiber (TDF) than the raw sample, due to the increases of both DF fractions. Under darkness conditions, germination exhibited the highest contents of IDF and SDF. Decreasing IDF/SDF ratios showed that the carbohydrate changes did not take place to the same extent during germination, the SDF fraction being the most affected. The detailed chemical composition of fiber fractions reveals increases of cellulose in the IDF of germinated samples, whereas SDF exhibits a decrease of pectic polysaccharides and also increases of polysaccharides rich in glucose and mannose. The DF results were corroborated by a comparative examination of the cell wall carbohydrate composition. 相似文献
77.
Tabera J Guinda A Ruiz-Rodríguez A Señoráns FJ Ibáñez E Albi T Reglero G 《Journal of agricultural and food chemistry》2004,52(15):4774-4779
Countercurrent supercritical fluid extraction (CC-SFE) at a pilot scale plant was used for fractionation of high-added-value products from a raw extract of olive leaves in hexane. Compounds found in the raw extract were waxes, hydrocarbons, squalene, beta-carotene, triglycerides, alpha-tocopherol, beta-sitosterol, and alcohols. The CC-SFE extraction process was investigated according to a 2(3) full factorial experimental design using the following variables and ranges: extraction pressure, 75-200 bar; extraction temperature, 35-50 degrees C; and ethanol as modifier, 0-10%. Data were analyzed in terms of extraction yield, enrichment, recovery, and selectivity. Higher extraction yields were attained at 200 bar. For most of the compounds analyzed enrichment was attained at the same conditions, that is, 75 bar, 35 degrees C, and 10% ethanol. Hydrocarbons were usually recovered in the separators, whereas waxes and alpha-tocopherol remain in the raffinate. Selectivity data reveal that alpha-tocopherol is the most easily separable compound. The influence of the experimental factors on the recovery of all the compounds was studied by means of regression models. The best fitted model was attained for beta-sitosterol, with R2 = 99.25%. 相似文献
78.
Serra-Majem L Ribas L Ngo J Ortega RM García A Pérez-Rodrigo C Aranceta J 《Public health nutrition》2004,7(7):931-935
OBJECTIVE: To evaluate dietary habits in Spanish children and adolescents based on a Mediterranean Diet Quality Index tool, which considers certain principles sustaining and challenging traditional healthy Mediterranean dietary patterns. DESIGN: Observational population-based cross-sectional study. A 16-item Mediterranean Diet Quality Index was included in data gathered for the EnKid study (in which two 24-hour recalls, a quantitative 169-item food-frequency questionnaire and a general questionnaire about socio-economic, demographic and lifestyle items were administered). SETTING: Spain. SUBJECTS: In total, 3850 children and youths aged 2-24 years residing in Spain. RESULTS: Of the sample, 4.2% showed very low KIDMED index results, 49.4% had intermediate values and 46.4% had high index results. Important geographical differences were seen, with subjects from the Northeast showing the most favourable outcomes (52% with elevated scores vs. 37.5% of those from the North). Lower percentages of high diet quality were observed in low socio-economic groups, compared with middle and upper income cohorts (42.8%, 47.6% and 54.9%, respectively). Large cities had more positive results and only slight variations were seen for gender and age. CONCLUSIONS: The KIDMED index, the first to evaluate the adequacy of Mediterranean dietary patterns in children and youth, confirms that this collective is undergoing important changes, which makes them a priority target for nutrition interventions. Results challenge certain commonly perceived notions tied to income level, population size and diet quality. 相似文献
79.
The environmental conditions of plants grown in a glasshouse were controlled by a minicomputer (IBM-Series 1). The simulation model thus developed provides better analyses of the relationship between yield increase and control of environmental factors.The glasshouse used was in several sections, with all the necessary devices for controlling environmental conditions. Two different climatic regimes were stimulated in order to find a better agreement of simulated values with experimental data.The computer used can be applied to a system comprising several glasshouses where different crops are grown. 相似文献
80.